Mark Cavendish, on the verge of a move to the biggest team in cycling, was narrowly beaten to a stage victory in the Tour of Britain yesterday in a controversial finish in which a missing barrier allowed riders to cut a corner, in Birmingham.

The 21-year-old is about to sign a permanent deal with T-Mobile, having impressed the German team in a short spell as a stagiaire, or triallist.

But he was disappointed yesterday, having failed to catch a break by Frederik Willems on the fourth stage of the tour. The Isle of Man-born cyclist surged ahead of Paul Manning, who complained bitterly that the front two had not followed the correct line round a roundabout inside the final kilometre.

"It's not good enough," said Manning. "It was a disgrace. I've said to the race director, 'Why do I bother riding my bike if you're going to mess up the finish?'" The race technical director Mick Bennett admitted: "The barrier should have been there," but declined to comment further.

Martin Pedersen leads as the race heads for the South-east and Canterbury.